iv.] ARTIFICIAL COMMA-BACILLI. 69 



nearly as good as Agar-agar meat-broth peptone. The 

 white of an egg, about 25 to 30 ccm., is dissolved in 220 ccm. 

 of distilled water to which 30 ccm. of liquor potassae is pre- 

 viously added. Boil till all is quite dissolved ; and after this 

 add 4 grms. of acid phosphate of potassium, whereby the 

 alkalinity is reduced but not quite neutralised ; then add i 

 p. c. of Agar-agar ; dissolve by boiling, filter, and decant into 

 test-tubes, which for sterilising are treated in the usual 

 manner. This egg albumen and Agar-agar mixture is of 

 good solid consistency even at 50 C., is beautifully trans- 

 parent, and is a very good solid nutritive medium for the 

 comma-bacilli, besides being very much cheaper (one egg 

 being greatly cheaper and easier to obtain than a pint of beef 

 broth or a tin of Brand's meat-extract) than the Agar-agar 

 meat-extract peptone. In this medium the comma-bacilli 

 grow in the same matmer as in the Agar-agar meat-extract 

 peptone mixture. 



(/) On linen. As Koch has pointed out, if the mucus- 

 flakes from the ileum of an acute case are placed on linen, 

 kept damp in a closed glass chamber at any temperature 

 between 20 and 36 C., a very excellent cultivation of 

 comma-bacilli is obtained. On examining these mucus-flakes 

 after twenty-four to thirty-six hours or a little later, crowds of 

 comma-bacilli are seen. In a fresh preparation many of 

 these are wavy or spiral chains or g-shaped forms, but on 

 making a permanent specimen by drying and staining most 

 of them are found broken up into single comma-bacilli. 

 T. R. Lewis has pointed out this difference (Appendix to 

 Report on Asiatic Cholera). After forty-eight hours, owing 

 to overgrowth of other bacteria present, the comma-bacilli 

 cannot be easily obtained pure ; but if originally the mucus- 

 flakes contain few other bacteria besides comma-bacilli, a 

 linen cultivation such as that described is a ready and 



